Not able to save to a created folder (applescript) - scripting

Question

so I have been trying to create a script that will create a folder on my desktop, then create a spreadsheet, and save the spreadsheet to said folder. here is the script...
set folderName to "Tester"
set FileName to "MayDay"
set SaveName to FileName & ".numbers" as string
set FilePath to "Macintosh HD:Users:Ryan:Desktop:" & FileName & ":"
tell application "Finder" to make new folder at desktop with properties {name:folderName}
tell application "Numbers" to activate
tell application "Numbers" to make new document with properties {name:FileName}
tell application "Numbers"
tell document 1
tell table 1 of sheet 1
merge range "B8:C8"
end tell
end tell
delay 1
tell application "Numbers" to activate
end tell
tell application "Numbers" to (save document 1) in FilePath
end
It has no problem making the folder, opening the spreadsheet, changing its name, and merging the cells, the problem comes in at the end when I try to save it.
I have tried adding (as numbers) no parenthesis after the save command, that errors out. After I run the script, and clear the crash, I can close out numbers and it will prompt me to save it in the "Tester" folder, but it won't do it on its own. insert grey hairs and headaches here.
I am really new to applescript, and I am hoping this is just a simple syntax thing, any help would be appreciated.
Thanks in advance!
R

Answer 1

Here's working code. A key is to use POSIX path and POSIX file and also the "save ... in ..." takes a file reference, not a string.
set folderName to "Tester"
set fileName to "MayDay.numbers"
set FilePath to (path to desktop as string) & folderName & ":" & fileName
set posixPath to POSIX path of FilePath
try
tell application "Finder" to make new folder at desktop with properties {name:folderName}
on error errMsg
end try
tell application "Numbers"
set myDoc to make new document with properties {name:fileName}
tell myDoc
tell table 1 of sheet 1
merge range "B8:C8"
end tell
end tell
delay 1
save myDoc in POSIX file posixPath
end tell